Simulation Study On Laser Propagation Through The Atmosphere In Optoelectronic Countermeasures

The optoelectronic countermeasures equipment are susceptible to atmosphericattenuation effects, atmospheric turbulence effects, thermal blooming effects and resultin performance degradation. In order to evaluate the impact of atmospheric conditionson the engineering applications of optoelectronic countermeasures quantitatively, thesimulation model according to the system structure on the performance ofoptoelectronic countermeasures equipment under various atmospheric conditions mustbe established.In this dissertation, based on the laser propagation through the atmosphere inoptoelectronic countermeasures, laser engineering applications in optoelectroniccountermeasures accord with the actual scene were modeled theoretically and simulated.The contents can be mainly divided into two parts. The first part is the modeling andsimulation about the folded optical path of laser propagation in atmosphere. Thereflection model in the optical path is cat's eye cooperative target and some otherexamples are analyzed. The second part is the modeling and simulation abouthigh-energy laser (HEL) propagation in the atmosphere. The main beam types of HELare annular beams and some other examples are analyzed. The main research resultscould be summarized as follows.A simulation model about the folded optical path of laser propagation inatmosphere with cat's eye reflection model has been developed. The echo characteristicsof distorted optical field caused by atmospheric turbulence propagation through cat'seye system have been studied by means of Collins diffraction integral equations. Theforward propagation and reverse propagation were also simulated according to the laserand atmospheric conditions. The results show that the echo probability is reduced withthe increase of turbulence intensity because of the spot energy dispersion at the cat's eyetarget, and the echo probability is also influenced by the cat's eye location. A simulationsoftware about folded optical path of laser propagation in atmosphere was developed onthis basis. These results provide guidance and reference for atmospheric laserengineering applications. A simulation model about the annular beam propagation in atmosphere has beendeveloped. Propagation properties, atmospheric turbulence effects, thermal bloomingeffect and combined effect of both about annular beams from unstable resonator havebeen simulated and analyzed. The results show that the thermal blooming has littleeffect on pulse high-energy annular beam. For continuous high-energy annular beamwhen the propagation distance is greater than the characteristic distance, the thermalblooming effect is similar to the gaussian beam. When the propagation distance is lessthan the characteristic distance, the thermal blooming effect is different from thegaussian beam. A simulation software about HEL propagation in atmosphere has beendeveloped. The effect of the annular beams from unstable resonator has been evaluatedfrom the beam quality and atmospheric channel conditions.Some examples of folded optical path model and HEL propagation in atmospherewere analyzed respectively. The algorithm of vibration signal demodulation underatmospheric turbulence state for homodyne laser vibrometer target identification systemwas proposed. An incoherent combining scheme of high-power fiber lasers based onadaptive optics components was proposed and the key parameters has been analyzed.The field experiments of laser horizontal propagation in atmospheric near groundhave been carried out and the experimental datas have been analyzed statistically.